When a cuff-type catheter is inserted into a body passageway, such as a trachea, the cuff is expanded by pressurized fluid so as to block the passage of aspirated air past the cuff. A visual pressure indicator positioned in the fluid-flow passage visually indicates when the cuff is in the expanded position.
Known pressure indicators such as U.S. Pat. No. 4,018,231 issued Apr. 19, 1977 require an additional closed central tubular passageway extending through the indicator to ensure that the pressurized air in the cuff can be withdrawn to collapse the cuff when a negative pressure has collapsed the walls of the indicator about the central passageway. This additional tube is costly to manufacture in relation to the price of the indicator and is itself subject to blockage if accidentally deformed. U.S. Pat. No. 4,016,885 issued Apr. 12, 1977 discloses a hollow circular tubular pressure indicator wherein the opposite sides of the indicator inherently collapse into abutting relation when vacuumized which may block the passageway through the indicator.